Field of the Invention
The present invention relates to a digital audio signal recording method suitably applied to the case such that an audio signal is recorded on an audio track of a motion picture film in a digital fashion.
Description of the Related Art
In motion picture films, an analog audio signal of about two channels is recorded on a so-called sound track which is formed in the vicinity of the picture area.
According to the recent progress in digital audio technologies, it can be known that an audio signal is converted into digital data and then recorded on a recording medium such as a magnetic tape or the like. Also in the motion picture films it has been requested that the audio signal be recorded on the motion picture film in the form of a digital signal.
In the case of motion picture film, however, the conventional sound track on which the analog audio signal is recorded cannot be removed to maintain compatibility with existing film projection apparatus. Therefore, a new track on which digital audio data can be recorded must be prepared in other portion than the sound track.
U.S. Pat. No. 4,600,280 describes a technique in which a digital audio signal is recorded on a motion picture film together with a conventional sound track. Also, U.S. Pat. No. 5,101,397 describes a technique in which an audio signal is recorded in the form of digital audio signal. Furthermore, U.S. Pat. No. 4,461,552 describes a technique in which an audio signal is encoded according to the pulse-code-modulation (PCM) system and then optically recorded on a film. However, the above-mentioned prior art fail to disclose an arrangement in which the words forming a digital audio signal are properly arranged on the film or the addition and arrangement of error detection and/or error correction for avoiding data error.